A 14-year-old boy dressed in military clothing is accused of stabbing a 22-year-old student in the neck at the University of Sydney on Tuesday morning, resulting in a campus-wide lockdown. The student was transported to Royal Prince Alfred Hospital in serious but stable condition. Police in Australia said the victim did not know his attacker. “A motive or ideology, importantly, has not been determined at this time,” said Mark Walton, the acting assistant commissioner for the New South Wales Police. “The ideology that may be related to this young person’s activity is unknown, but I would say it…